P0604

DTC P0604 Internal Control Module Random Access Memory (RAM) Error





Circuit Description
A normal function of the Transmission Control Module (TCM) programming is to perform an internal check that verifies the integrity of the RAM memory allocations.
The DTC P0604 sets when the Random Access Memory (RAM) is not operating correctly when checked on initialization. An area of RAM is failed a read/ write test.

Conditions for Setting the DTC
- An area of RAM is failed a read/ write test.
- System voltage is too high or too low.
- Transaxle input voltage is too high or too low.
- Immediately after the above condition occurs.

Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
- The TCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
- Adopt Emergency/ Substitute mode and constant 4th gear by hydraulic control.
- After ignition OFF/ON: 3rd gear by hydraulic control. Possible P, R and N also possible.
- Power supply cut off to the EDS valve.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF when the malfunction has not occurred after three-ignition cycle.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- Using a scan tool can clear history DTCs.

Diagnostic Aids

Steps 1-5:

- When DTC P0604 sets, the replacement of TCM is recommended.